By the look of the Wearable Gaze Detector — with its many protruding wires and Cyberman-esqe design — it would have to do something pretty amazing to be worth committing the fashion felony of actually putting it on your head. Well, you see those rectangular thingies on top of each ear cup? Those are tiny video cameras, each tracking your eye movements by detecting the changes in electrical potentials that happen when they move. The idea is the Gaze Detector would record everything you're looking at, so later on you could watch a movie of your day with an accompanying "attention marker" pointing out exactly what held your gaze. Paired with a Web browser, the program could automatically call up information on the objects you looked at. Saw a nice painting as you walked through a building lobby? Review the video and find out who's the artist. Caught a glimpse of a cool car? Call up its make and model and where you can get the best price. Creator Manabe Hiroyuki would obviously have to do a lot of work on the design to turn the gaze detector into something you'd actually want to wear, but the eye-tracking technology certainly catches our attention.
The short answer is "no", but it is a qualified "no" because there are odd ways of interpreting the question which could justify the answer "yes". Light is composed of photons so we could ask if the photon has mass. The answer is then definitely "no": The photon is a massless particle. According to theory it has energy and momentum but no mass and this is confirmed by experiment to within strict limits. Even before it was known that light is composed of photons it was known that light carries momentum and will exert a pressure on a surface. This is not evidence that it has mass since momentum can exist without mass. [ For details see the Physics FAQ article What is the mass of the photon? ]. Sometimes people like to say that the photon does have mass because a photon has energy E = hf where h is Planck's constant and f is the frequency of the photon. Energy, they say, is equivalent to mass according to Einstein's famous formula E = m
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